Incandescent lamp.



F. SKAUPY.

INCANDESCENT LAMP.

APPLICATION FILED NOV. 3. 1910.

1 1 59, 1 1 1 Patented Nov. 2, 1915.

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FRANZ SKAUPY, OF BERLIN, GERMANY, ASSIGN OR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

INCANDESOENT LAMP.

Specification of Letters Patent.

Patented Nov. 2, 1915.

Application filed November 3, 1910. Serial No. 590,499.

To all whom it may concern:

Be it known that I, FRANZ SKAUIY, a subject of the Emperor of Austria-Hungary, residing at Berlin, Germany, have invented certain new and useful Improvements in Incandescent Lamps, of which the following is a specification.

The object of the present invention is to increase the useful life of incandescent lamps and to prevent or hinder the formation of light obscuring deposits on the bulbs thereof.

The invention is of advantage in connection with lamps having metallic filaments, as, for example, tungsten filament incandescent lamps.

In the accompanying drawings, Figure 1 is a view of an incandescent lamp and illustrates one way in which substances that may be employed for the purposes of my invention may be arranged in the lamp globe; and Figs. 2, ,3, 4, 5 and Gshow structures that will be hereinafter referred to.

It is well known that tungsten and other filaments disintegrate or evaporate in the so-called vacuum of the lamp globe. This disintegration or dissipation seems to be dependent upon the character and amount of the gas or vapor remaining in the lamp after exhaustion or gradually developing from the difierent parts of the lamp. I have discovered that the introduction of various substances into the lamp globe produces a favorable effect on the life and illumination of the lamp, by minimizing the formation of light obscuring deposits on the lamp globe. Moreover, the employment of such substances as my invention contemplates has the advantage that disintegration products actually appearingeven assuming equal quantities of materialgive to the glass wall of the lamp a color lighter than usual, so that the decrease in illumination is retarded.

In particular, I have employed various halogen compounds for the purposes of my invention, especially inorganic or metallic halogen compounds. At the temperatures which these substances assume in the lamp exposed as they are to the heat and other radiations from the filament and under the conditions of use, there seems to exist in the evacuated lamp a halogen-containing atmosphere which is of immeasurably small pressure (halogen-pressure) and about that of a nearly perfect vacuum, as the evacuated lamp responds to the customary spark coil test in the same way as a first-class standard vacuum lamp of the prior art. The gases or vapors of this halogen containing atmosphere seem to be at least a factor in the production of the benefits of my invention. Although the halogen containing atmosphere is so slight in amount and of such low pressure that it can scarcely be detected, yet it is sufficient to render the deposits on the bulb very much more translucent than the deposits formed in a similar lamp which does not contain the halogen compound. It may be that progressive development of the halogen containing atmosphere at this pressure occurring when such substances are used has a favorable eifect by converting into halogen compounds traces of hydrogen and other electro-positive gases or vapors developing in incandescent lamps during use.

Another explanation of the mode of operation of my invention is that the halogenous vapors progressively evolved during the operation of the lamp are activated or in some way afl'ected by the glowing filament so as to combine with metal driven off or evaporated from the filament to form a chemical compound whereby such deposit as may occur on the Walls of the bulb appears to be lighter in color and also smaller in amount than would otherwise be the case.

lVhen the effects on the lamps are favorable, pressures of halogen-containing gases cannot be greater than the limits of measurability or substantially the same as what is known in the art as a first class vacuum, that is, a pressure of about one micron or one one-thousandth of a millimeter of mercury. Pressures corresponding to mm. mercury are much too great and lead to the early destruction of the filament if they exist continuously in the lamp. By reason of its smallness, the pressure could only be ascertained indirectly by determining the pressure at a number of higher temperatures and calculating by extrapolation the ressure for the temperature in question. t is known that if the residue of gas is not entirely removed from them and a pressure of a few hundred-tbs of a millimeter of. mercury still remains, incandescent lamps give a glow like Geissler tubes if the lamp is taken in the hand and its current terminals connected with one pole of an induction coil having a spark-gap about 1 CM. long. Lamps in accordance with the present invention do not give such a glow, but behave in this respect like the old normal well evacuated incandescent lamps. It can scarcely be said, therefore, that in the sense of the pressure measurements heretofore used in the incandescent lamp art any pressure of halogen or of a halogen compound exists in the lamp.

I have hereinafter given such information as will enable those skilled in the art to employ my invention in the most advantageous manner known to me, irrespective of any theory as to how its benefits are produced. All of the halogens form some inorganic compounds which have when in the lamp a vapor pressure suitable for the purposes of my invention and which may be used with advantage.

At the head of the substances that may be employed for the purposes of my invention stands, in my experience, thallic thallous chlorid (TlCl .3TlCl, thalli-thallochlorid or thallic chlorid (T101 thallichlorid), which even on moderate heating during the exhausting of the lamp is transformed into the first-named double compound as well as the double compounds of the thallic chlorids with other chlorids. Thallic chlorid may be used along with potassium chlorid, the substances being ground up together, and the proportions 3KCLT1G1 giving good results. Other substances which act very well are the following: dichlorid of platinum (PtCl, platinchloriir )instead of which the ordinary tetrachlorid of platinum (PtCl platinchlorid which on even moderate heating gives dichlorid, may be used; dried ferric chlorid hydrate; and tri-potassium hydro-plumbi-fluorid (3KF.HF.PbF and tri-potassium plumbi-flu0rid (3KF.PbF

The substances usedeither alone or mixed with indifferent and non-volatile material-may be placed in a small tube located in the middle of the incandescent lamp globe between the filaments before the lamp is evacuated, and the ordinary middle support (usual in tungsten lamps, for example) may be made tubular or hollow and utilized as a receptacle. This is illustrated by Fig. 1 of the drawings, in which a indicates the substances employed thus arranged in the hollow member or standard 8 of the filament system or mount and prevented from falling out during transportation or when the lamp is hung obliquely or perpendicularly by a layer 6 of transparent material,for example, glass wo0l,or of ignited asbestos.

When the substances employed are placed in the central standard or stem of the filament supporting system, it sometimes happens that material passing out of the stem causes a deposit on the portion of the globe wall opposite the free end of the stem, which interferes with the illumination from the lamp and gives the lamp an unsightly appearance. These drawbacks can, I have discovered, be done away with by a depositcatcher forming an extension of the stem. Fig. 2 shows this feature of my invention. As in Fig. 1, a indicates the substance employed arranged in the hollow stem 8 of. the filament-supporting frame and prevented from falling out by the layer Z) of transparent material. (J is the deposit-catcher on the stem, shown as a hollow sphere having an opening into the lamp globe opposite that from the hollow of the standard into it. In Figs. 2-5 are illustrated different forms of construction of the continuation of the stem which show that the result aimed at may be attained not only by small receptacles or umbrella-like surfaces arranged on the end of the stem, but by suitably curved prolongations of the stem tube as well.

In detail, Fig. 3 shows a spherical catcher having a number of small openings adjacent its junction with the stem; Fig. 4 shows in section an umbrella-like hood mounted over the open end of the stem tube; Fig. 5

shows a prolongation of the stem tube bent in a zigzag; and Fig. 6 shows a prolongation of the stem tube curved back on itself and around to its original direction again.

It is to be observed that when halogen compounds developing from the substances employed and free halogen coming off therefrom attack the filament, the attack is more powerful at the points where its temperature is highest, so that filaments which are defective in spots or which are not of uniform thickness are in such case liable to be burned out more rapidly in lamps constructed in accordance with my invention. Hence it may be preferred that filaments be from the beginning of uniform thickness and of perfectly uniform incandescence.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. An incandescent lamp having a tungsten filament and an inorganic halogen compound in said lamp adapted to cause therein during normal operation of the lamp a halogen containing atmosphere having a pressure not exceeding that of a first-class vacuum and chemically active toward the material of the filament to combine with material driven off from the filament and render the deposit on the bulb less light obscuring than would be a deposit of uncombined material from the filament.

2. An incandescent lamp having a metallic tungsten filament, and an inorganic compound in said lamp adapted to generate therein at the temperature attained during normal operation of the lamp an atmosphere having a pressure not exceeding that of a.

first class vacuum and chemically active toward tungsten to render the deposit on the bulb less light obscuring than would be a deposit of tungsten.

8. An incandescent lamp having a metallic tungsten filament, and an inorganic halogen compound in said lamp having a vapor pressure which causes said compound to produce therein during normal operation of the lamp a halogen containing atmosphere at a pressure not exceeding that of a firstclass vacuum.

4. A tungsten filament incandescent having therei n a halogen compound of thallium which generates at the temperature attained during normal operation of the lamp an atmosphere of a pressure not exceeding that of a first class vacuum.

An incandescent lamp having an open receptacle therein, an inorganic compound in said receptacle adapted to generate during the normal operation of the lamp an atmosphere at the pressure of a first class vacuum and chemically active toward the material of'the filament, and means at the opening of said receptacle for receiving deposits of material passing out therefrom.

6. A tungsten filament incandescent lamp having a hollow support and a tungsten filament mounted thereon, and a halogen compound of thallium contained in said hollow support, said hollow support opening into the lamp bulb.

7. An incandescent lamp bulb provided with a hollow standard therein, a tungsten filament carried by said standard, a halogen compound of thallium contained in said hollow standard, and an extension of said standard constituting a deposit receiving chamber for matter emanating from said halogen compound.

8. The combination with a tungsten filament incandescent electric lamp, of a metallic compound within the lamp bulb and exposed to heat radiations from the filament for revolving during operation of the lamp a substance in gaseous form and of the pressure of a first-class vacuum, which upon activation by the glowing filament is capable of combining with metal evaporated from the filament to form upon the bulb a deposit less light obscuring than would be a deposit of metal from the filament.

9. The combination with a tungsten filament incandescent electric lamp, of a halogen compound of thallium Within the lamp bulb and exposed to heat radiation from the filament for evolving during operation of the lamp an atmosphere which is so afl'ected by the glowing filament as to prevent discoloration of the lamp bulb.

10. The combination with a metallic filament incandescent electric lamp of a vaporizable metallic halogen compound mounted in the lamp bulb in proximity to the filament and capable of giving oil during operation of the lamp gaseous matter at a pressure not exceeding that of a first-class vacuum which will at that pressure combine with metal evaporated from the filament to form a compound.

11. The combination with a tungsten filament incandescent electric lamp having therein a substance for preventing blackening of the globe and for lengthening the life of the lamp consisting of potassiumthallium chlorid.

In witness whereof, I have hereunto set my hand this twenty-first day of October,

FRANZ SKAUPY. Witnesses:

WOLDEMAR HAUPT, HENRY HASPER. 

